I didnt check the sources in his bibliography, but I think he cites it from a couple of different places, including the Congressional Record.
I'm afraid the Congressional Record (at least in this context) doesn't really qualify as worthwhile. Any congresscritter, including Maxine Waters, can place *anything* in there (and often have). What seems to have happened is that a congresscritter from 1963 took a section from a 1958 Skousen Book and slapped a label on it e.g. "Communist Goals of 1963" and the circle goes round and round.
In short, the document (and its hyperventilated "Dr. Evil" like wording) appears to be Skousen's creation, more properly his "interpretation" of Communist goals based on other sources which he does not specifically name. I could be wrong but nobody has given me any reason to believe otherwise.